Modern fabric trim covers and their interconnected spring and cushion components (collectively termed “upholstery”), such as those used in vehicles, are often carefully sculpted and shaped to produce a comfortable and aesthetically pleasing effect. As such, the fabric (typically cloth, vinyl or leather with an appropriate backing material) is secured at many locations along its surface to a resilient or flexible backing that defines the cushioned substrate of the upholstered item (for example, a seat bottom, cushion, back or headrest). In general, the close-fitting appearance of the upholstery to the substrate requires that the fabric be tacked down to the substrate at any intermediate surface contour dips, Vees or trenches in the surface. Otherwise, the fabric will tend to billow out or “tent” at these non-planar surface features.
One approach to efficiently and securely attach trim covers to a foam substrate involves the use of resilient polymer trim clips that are embedded in, and adhered to, the foam. With reference FIG. 1, an example of an upholstery clip 100 is shown embedded in a foam substrate 102. The upholstery clip 100 resides within a trench 104 formed in the substrate 102. The clip 100 in this example is a low-profile clip as described in commonly assigned U.S. Pat. No. 8,099,837, entitled LOW-PROFILE UPHOLSTERY CLIP FOR ATTACHING A BEAD TO A FOAM SUBSTRATE, the teachings of which are incorporated herein by reference as useful background information. This exemplary clip 100 includes a planar (flat) rectangular base 110 and an upwardly directed clip member 150 with associated legs 160, and inwardly and downwardly directed barbs 170 adapted to capture a listing bead through a gap 180 therebetween, as described below.
The clip base 110 in this example includes formations 112 and 114 on opposing ends, which are optional and allow for a “festooning” arrangement, wherein clips can be snapped together in a variable-length, flexible chain during storage and distribution by engaging each cylindrical formation 114 with an overlying C-formation 112 on an adjacent clip. Versions of these festooning clips are described in commonly assigned U.S. patent application Ser. No. 13/787,929, entitled FESTOONED TRIM CLIP SYSTEM AND METHOD FOR ATTACHING FESTOONED CLIPS TO A SUBSTRATE, the teachings of which are incorporated herein by reference. Before foam is injected into a mold cavity, the installer peels each clip off of the chain by removing the cylinder formation 114 from an adjacent C-formation 112, and applies it to an appropriate location (e.g. along a trench) within mold cavity. In alternate embodiments, a clip base can have a key on the bottom that can be fit into a corresponding slot on a hard anchor base so that the clip can be turned and locked into place, as described in commonly assigned U.S. patent application Ser. No. 14/534,104 entitled UPHOLSTERY CLIP FOR REMOVABLE ATTACHMENT TO RIGID SURFACES, the teachings of which are incorporated herein by reference. Other embodiments of clip bases, such as hooks on the bottom of the clip, or other arrangements for securing the clip in place, will be understood by a person having ordinary skill in the art.
FIGS. 2 and 3 show the installation of a typical, prior art listing bead 210 into a low-profile clip in accordance with this embodiment. In FIG. 2, the listing bead 210 is attached at the end of a web 220 (a fabric), which is, itself, attached to an overlying upholstery piece (not shown). The exemplary listing bead 210 can be formed as a continuous extrusion from an acceptable polymer, and includes a pair of upper walls 230 that are defined at an approximate angle AW with respect to the horizontal line 231. The bead upper walls 230 are arranged to engage the bottom faces 232 of the barbs 170. During assembly, the listing is driven downwardly (arrow 250) toward the gap 180 between the clip member legs/barbs. The maximum width WGB of the listing bead 210 is wider than the width of the gap 180 when the legs are in a resting (unsprung) arrangement. Thus, the listing bead 210 can deform slightly as its rounded lower faces 260 pass through the barbs 170, and the reduced thickness legs 160 flex outwardly (outward arrows 227) in response to the pressure applied by the bead 210 as it engages the rounded ends of the barbs 170.
In FIG. 3, the bead 210 has passed fully through the gap 180 and is now resting (bottomed-out) against the base 110. So long as the central region of the clip is high enough to allow the upper walls 230 of the bead 210 to clear the bottom faces 232 of the barbs 170, then the clip legs 160 are allowed to flex back (inward arrows 320) into their original resting (unsprung) shape. After installation, the natural tension placed upon the attached upholstery covering will generally bias the upper walls 230 of the listing bead into firm engagement with the bottom faces 232 of the barbs 170. This tension, and the relatively close conformance of widths of the clip central region and bead (as shown in FIG. 3), ensures a rattle-free interconnection between the foam substrate and trim cover.
While the above-described, exemplary clip and listing arrangement provides an efficient and reliable mechanism for joining trim covers to foam substrates, it allows the listing bead to slide longitudinally within the clip. After installation, the clip holds the listing bead in two dimensions, but relies on limited friction between the bead and the insides of the legs to limit movement of the bead longitudinally within the clip. This longitudinal movement of the listing bead can affect the appearance of the entire seat trim cover. Accordingly, it is desirable to secure the listing bead and upholstery clip in all three dimensions relative to each other to securely hold the listing bead, and thus the seat cover, in place.